Electronics > Beginners
Power supply advice please (I live in the UK)
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tggzzz:

--- Quote from: rstofer on December 07, 2018, 09:06:00 pm ---
--- Quote from: tggzzz on December 07, 2018, 08:48:30 pm ---In that respect, old analogue scopes are better than digitising scopes, since they are simpler and all the controls are on the front panel, not hidden in a menu system. But if you have a digitising scope and can use it, that isn't a reason to get a working analogue scope.

--- End quote ---

Having used my DS1054Z, I see many advantages over my Tek 485.  In fact, the only thing the 485 brings to the dance is bandwidth.  Bandwidth is cheaper when buying used analog scopes.  For the Arduino style projects and reasonable < 100 MHz projects, a 100 MHz digital will be excellent. 

--- End quote ---

100MHz is OK provided the signal integrity is good. The killer-app for DSOs is one-shot analogue events.


--- Quote ---Four channels is more than twice as good as two channels.  This shows up quickly when working with SPI transactions.

--- End quote ---

Mutter. Three is better than two, but with thought and imagination two is often sufficient. Any more and I want a logic analyser or printf statements :)


--- Quote ---If I were just learning and tending to roll around like a BB in a bowling alley, I would go for the AD2.

--- End quote ---

I have an AD1, and I agree. In fact the combination of AD+Tek485 (or equivalent) is sufficient for most amateur electronics.


--- Quote ---Electronics is played in a very large sandbox with many areas of interest.  Just find a corner and dig in!

--- End quote ---

Yes indeed.

Choose a tool that will do the job at hand. A "perfect" tool will do it faster (excluding learning curve) but not necessarily better.

It wlll be interesting to see if the OP is still reading :)
rstofer:

--- Quote from: CJay on December 07, 2018, 09:11:05 pm ---Well to be far, you did get a PSU right away, it just wasn't variable.

A PSU of some sort is essential, doesn't matter if it's batteries, a fixed supply, home made or bought, it all depends what's available in your budget/needs, as tggzzz says, you have to be able to define your needs.

--- End quote ---

My little 5V 3A power supply didn't cost anywhere near the $473 my DP832 cost.  Yes, you need a source of some kind but it doesn't have to be a do-all end-all network programmable bench model.

Particularly for PSs, there's a tendency to go in one of two ways:  1) Try to build a high end PS, similar to a $500 supply with voltage adjust/limit and current adjust/limit, using an entirely incompatible transformer (because real supplies use custom transformers), and do it for $29.95 OR 2) buying something that is marginal in delivered power quality because it is cheap.

For 'small' projects, these Power Bricks are interesting.  They work especially well if your hub as a couple of power only ports.

https://store.digilentinc.com/powerbricks-breadboardable-dual-output-usb-power-supplies/

I think I would try to defer the high dollar approach to buying a quality supply as long as possible - but no longer.  There are other tools that are more important.

I might build a triple output fixed voltage supply:   +-15V and +5V each at about 1A.

I just this minute won the $1 bid for a new triple output fixed supply:

https://www.ebay.com/itm/POWER-ONE-HTAA-16W-A-LINEAR-TRIPLE-OUTPUT-REGULATED-POWER-SUPPLY-NEW/312347229694?

$15 shipping, bummer...

A supply like this will work well for just about everything.  There is the downside of it not having adustable current limiting - a high end supply will have this feature and it can save a lot of money on magic smoke.

Look around eBay and save the high dollar expense until much later (if ever).
CJay:

--- Quote from: rstofer on December 07, 2018, 09:42:50 pm ---
--- Quote from: CJay on December 07, 2018, 09:11:05 pm ---Well to be far, you did get a PSU right away, it just wasn't variable.

A PSU of some sort is essential, doesn't matter if it's batteries, a fixed supply, home made or bought, it all depends what's available in your budget/needs, as tggzzz says, you have to be able to define your needs.

--- End quote ---

My little 5V 3A power supply didn't cost anywhere near the $473 my DP832 cost.  Yes, you need a source of some kind but it doesn't have to be a do-all end-all network programmable bench model.

--- End quote ---

That's pretty much my point, you do need a PSU of some sort, the Thurlby and Farnell ones I mentioned often crop up around £30 on eBay, absolutely ideal. Those Power One supplies are really useful, LM723 based usually and bombproof as well as low noise, I used a triple output version for a number of years and probably still would if I knew where they went when I  moved.
rstofer:

--- Quote from: tggzzz on December 07, 2018, 09:16:33 pm ---
--- Quote ---Four channels is more than twice as good as two channels.  This shows up quickly when working with SPI transactions.

--- End quote ---

Mutter. Three is better than two, but with thought and imagination two is often sufficient. Any more and I want a logic analyser or printf statements :)


--- End quote ---

I have used imagination and gotten by for decades but there comes a point where the price of fully featured entry level scopes is compelling.  Not necessary but fun to play with!

printf() is my favorite way to debug digital systems.  It doesn't tend to work well for FPGA projects but for embedded projects, it is the way to go.

Dual channel analog scopes, particularly those with External Trigger Input, can be used.  But the modern DSO is so much more fun to play with!
cdev:
Do beginners absolutely need current limiting ability in a power supply?

So that IF something is hooked up wrong it won't fry the device-

Its so that I can set a ceiling of current the supply will deliver thats just a bit above what its expected power draw will be.  Most also have an indicator that tells you if that level is exceeded immediately.

With the bench supply, I can ensure that even if I short something out the amount of energy available to do things is what it needs, and no more.

You could get this kind of current limiting with any supply that delivers adequate voltage by adding a very inexpensive Chinese buck (DC-to-DC) converter add on. Some even add voltage output above the input voltage (buck-boost conversion)

If you already have a power supply, like a re-purposed computer ATX supply, add one of those DC to DC converter modules you're all set for many kinds of things.

Dave has done a video about them.

That route will just cost a few bucks, in its simplest form, if you already have the power supply you use it with.

These DC converters only cost a few bucks. But they have some issues. Noise is one. Build quality is another. The heat sinks they use are arguably inadequate for the tasks they try to do. But in most cases, if you enclose it in a proper case, and add a properly sized fuse to this supply so it will shut off if it has a problem, they will work fine, and be safe, and for the price are really a good deal.

But whatever you use, if it lacks current limiting, it isn't really ideal for prototyping, so isn't really a bench (i.e. experimenters) supply.

That why if you can find a good UK built bench supply, that you can afford, thats a very good investment you likely wont regret. As you'll likely keep it and use it frequently, for a long time.
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